Pregnanes and method of preparing the same



2,742,461 EGN N A D METH D 3 PREP RING.

Seymour Bernstein, Pearl. River, N.- Y., and Robert H.

Lenhard, Ridgefield Park; N. J., assignors to American yan mid G mnytNew Qrk,-,N- Y a rp a No Drawing. Aqiplication' August-16', 1955i,Serial-No. 450,246 7 cl m. (cl- 260-13155).

This inventionrela-tes to' new. pregnanes. More partic:

'ularly, it relates to, derivatives. of hydrocortisone; and

methods of preparing the same. a

The discovery of the highly desirable activity, of cortisone. in thetreatment. of rheumatic diseases and other pathological conditionsisnow. well. known. While cortis'one and-related compounds such ashydrocortisone, are highly active, they produce certain side reactionswhich are distinctly undesirable and which limit a wider use of suchcompounds except under careful: observation. It is also well known thatcompounds such as cortisone, when administered to adrenalectomiz'ed 'oradrenalectomizedv gonadectomized animals causes distinct; involution inthe thymus. This affect. has, been adapted fer a bicas in; determiningthe activity of adrenocorticalhormones The rim a idsb e p nt nventi 'aeresnane-h 1 lfi,l7a,2'l;-tetrol-3,205dione, in t ties similar tocortisone andhydroc rtrsone.

T e io p f h p e n nv i anr an be l u trated by; the. following generalform a:

OH. in which R is a member of the group consisting of hydrogen and lowerfatty acid ac'yl radicals, and derivatives thereof in which the 3 and 2-ear bonyl group are protected by lower alkylene ketals. 7 Thesecompounds are moderately soluble in acetone an ar at v y s lub e n a Thehave cmiga 'yi gh meltin p ints, (usua y:abQve.2QQ.) i

The m oundsl of the. resent nventie r tempe d by using asstart'ingmaterial bis-lower alkylene ketals of pregnene esters. The generalreaction can be illustrated by the following equation-z CHQOR:

CHzOR td s tgs Patc f ass y l ih ac e V50 rated saline and water.

onion --01; ..HO J 10 0 hydrolysis P/ 0 t. 7 0H in'which R is. hydrogenor a lower fatty acid acyl radi cal; and R' is a lower alkyleneradical.

In the above reaction R can be an acyl radical such as acetyl,propionyl, butyryl, valeryl, caproyl, and the like. The lower alkyleneketalgroups can be, forexample, ethylene .ketal, propylene ketal, methylpropylene and the like, in which R would be ethylene, propylene, andmethyl propylene, respectively.

In carrying outthe. present process theA -pregnene inv a solvent suchas. chloroform, carbon tetrachloride; ethyl acid; ormonopierphthalicacidat room temperature; The produet obtained, is the corresponding mixtureof preg 3O nane-5,6-oxides, that is. the alpha and-beta. oxides, The

to produce the alpha and beta oxides in-.-a pure state. Reduction of thealpha. oxide with lithium aluminum hydride affords the 5-a -hydr'oxylderivative. The. latter may alsoflbe prepareddirectly from the mixtureof the oxides without preparation. The ketal. "groups can be. removed byhydrolysis as shown hereinafter in the examples; to produce pregnane-Sa,1 1 3,17a,2-1-tetroI-3,20-dione.

Th pllo wing examples describe in detail the prepara- Qfrpreschtativecompounds of the present invention.

Example 1 Aii l gnene-llfi. 7 -t o ,20- i e2 mm3 20 bisethylene kefal-(-hydrocortisone acetate bisethylene ketal). 6.23 g.) inchloroform(301111.) was treatedwith perbenzoic acid (1.9g) in ethyl acetate (66ml.) at room temperature for 5 days. Additional ethyl acetate was added,and; the reactionrnixture was washedseveral times t 5 aqueq p a si m h rde fc d; y sam- After being dried over magnesium sulfate, the extractwas evaporated under reduced pressure to afford a white crystallinesolid.

v The mixture was dissolved in tetrahydrofura-n (@250 an d ether 5.0ml). Lithium aluminum hydride (3.0. g was addedand the mixture wasrefluxed for '4 hours (and then allowed to stand at room-temperatureovernight). The. excess hydride was decomposed. can tiously'with water,ethyl acetate was added, and theiinorganic precipitate was removed byfiltration. The solid was triturated several times with. benzene-ethylacetate.

Theextracts were combined, washed with saturated saline and water, driedand evaporated under reduced pres: sure. This afforded a whitecrystalline solid which wa s dissolved in pyridine (15 ml.) andacylatecl-wi th. acetic anhydride (seven and one-half ml.) (4. days atroom-temperature), The mixture was poured into. ice-water, and

. was extracted with; ethyl acetate. The extract was washed withsaturatedsaline and, water and was dried over magnesiumsulfate.Evaporation under reduced pressure gave a White, crystalline solid whichwas crystallized from acetone-petroleum ether to afford 2.35 g meltingpoint 297- I 7 227 C., with previous softening. Further recrystallizag:tion did not appreciably alter the wide range melting acetate, etc. istreated with a pe'racid such asper'benzoic mixture of oxides may beresolved bychromatography point; melting point 209-227 C., with previoussoftening. The latter solid together with its evaporated mother liquorwas dissolved in benzene (200 ml.) and absorbed on a silica gel column(120 g., ether washed and re-dried at 110 C.). The product was elutedwith one liter of 5% acetone-ether, and was crystallized fromacetonepetroleum ether to give practically pure pregnane-5a,1118,-17a,21-tetrol-3,20-dione Ill-acetate 3,20-bisethylene ketal, 0.97 g.,melting point 228-230 C., with previous softening. Three furthercrystallizations from acetone-petroleum ether gave purepregnane-5a,11fi,17a,2l-tetrol-3,20- dione 21-acetate 3,20-bisethyleneketal, melting point 231-233 C., with previous softening; [u] +4-.1(chloroform) Example 2 The bisethylene ketal of hydrocortisone acetate(3.0 g.) was dissolved in chloroform (18 ml.) and 1.27 g. of perbenzoicacid in ethyl acetate (25 ml.) was added. The mixture was allowed tostand at room temperature for 6 days. It was then poured into 50 ml. ofsaturated sodium carbonate and the product was extracted with ethylacetate. The extract was washed with water, dried and evaporated underreduced pressure. This afforded 3.2 g. of a colorless glass. The glasswas dissolved in 25% chloroform-benzene (40 ml.) and was adsorbed on acolumn of 200 g. of alumina. Elution with 50% chloroform-benzene (200ml.) gave 300 mg. of crystals (Fraction 1), and elution with 60%chloroform-benzene (400 ml.) gave 1.1 g. of crystals (Fraction 2).

Four crystallizations of Fraction 1 from acetonepetroleum-ether gave 138mg. of pure pregnane-11fi,l7a,- 21-triol-3,20-dione-5;3,6B-oxide21-acetate 3,20-bisethylene ketal, melting point 206207 C.; [a] +17(chloroform) Four crystallizations of Fraction 2 fromacetonepetroleurn-ether gave 440 mg. of pure pregnane-llfl,l7a,-21-triol-3,20-dione-5a,6a-oxide 21-acetate 3,20-bisethylene ketal,melting point 259261.5 C.; [a] 39 (chloroform) Example 3 The5u,6oc-0Xide (about 700 mg.) of hydrocortisone acetate bisketal wasdissolved in tetrahydrofuran (90 ml.), and lithium aluminum hydride(1.25 g.) was added. The mixture was refluxed for 3 hours, cooled, andwas treated cautiously with water. Ethyl acetate (200 ml.) was added andthe inorganic precipitate was removed by filtration. The product wasworked up by extraction with ethyl acetate. Evaporation gave a whitepowder which was recrystallized from acetone-petroleum ether. This gave410 mg. of pregnane-5a,1lfi,17a,21-tetrol-3,20- dione 3,20-bisethyleneketal, melting point 258261 C.

Example 4 This batch of 5oc,11f3,17oc,21-t6t101 bisketal was acetylatedat room temperature (72 hours) with acetic an hydride (1.5 ml.) withpyridine (4 ml.). Addition of water gave 390 mg. ofpregnane-5a,11B,17a,21-tetrol- 3,20-dione 21-acetate 3,20-bisethyleneketal, melting point 227 -230 C. Its infrared absorption spectrum waspractically identical with that of Example 1.

Example 5 The bisethylene ketal ofpregnane-5a,llfl,l7a,2ltetrol-3,20-dione 21-acetate (0.50 g.) wassaponified by being refluxed for one-half hour with two and one-halfpercent alcoholic potassium hydroxide (12 ml.). Water was added to thecooled solution and it was allowed to stand overnight at 5. The crystalswere collected and washed with water. In this manner there was obtained0.40 g. of pure pregnane-5a,11;8,17a,21tetrol-3,20-dione3,20-bisethylene ketal, melting point 261.5 264 C., with previoussoftening. Recrystallization from acetonepetroleum ether did not alterthe melting point; [e] 6.5 (chloroform) 4 Example 6 The bisethyleneLetal (0.42 g.) was dissolved in methanol (23 ml.), and was hydrolyzedby being refluxed for 10 minutes with eight and one-half percent (v/v)sulfuric acid (2.3 ml.). Water was added and the solution wasneutralized with sodium bicarbonate. The mixture was saturated withsalt, and one being scratched gave crystals which were collected byfiltration. In this manner there was obtained 0.12 g. of crudepregnane-5e,llfi,- l7a,21-tetrol-3,20-dione, melting point 25l.5-255 C.,with previous softening, browning and decomposition. Twocrystallizations from acetone improved the melting point, but did notremove the small amount of 15 -3- ketone found present in the crudematerial. Consequently, the crystalline material, mother liquors and abenzene extract of the reaction mixture were combined and evaporated todryness. The solid residue was dissolved in methanol ml.), and wasextracted ten times with 100 ml. portions of benzene. The aqueousmethanol phase was evaporated under reduced pressure (the water wasdistilled azeotropically with benzene). Several crystallizations fromacetone gave 5 3 mg. of pure pregnane-Sa,l1,8,17a,21-tetrol-3,20-dione,melting point 26l264 C., with previous softening, browning anddecomposition; ultraviolet: Xmas: none (end absorption only); thematerial gave a positive Blue Tetrazolium test diagnostic for thea-ketol group; [A -H5 (pyridine).

Example 7 CHQO It CH3 I g/L on in which R is a member of the groupconsisting of hydrogen and lower fatty acid acyl radicals and X is alinking group selected from the groups consisting of (b0 and where R isa lower alkylene radical.

2. Pregnane-5a,1118,17a,2l-tetrol-3,20-dione.

3. Pregnane-5a,11 3,l7a,21-tetrol-3,20-dione 21-acetatc.

4. Pregnane-5a,11B,l7a,21-tetrol-3,20-dione 3,20-bisethylene ketal.

5. Pregnane-5u,l1,6,17a,21-tetrol-3,20-dione 21-acetate 3,20-bisethyleneketal.

6. A method of preparing pregnane-5a,11/3,17a,21- tetrol-3,20-dionewhich comprises reacting a n -pregnene-11B,17a,21-trio1-3,20-dione-5a,6a-oxide 21-lower fatty acid ester3,20-bis-lower alkylene ketal with lithium aluminum hydride in thepresence of a solvent, adding a mineral acid to hydrolyze the resultinghydroxy pregnane and recovering said compound therefrom.

7. A method of preparing pregnane-5a,11}3,l7a,2ltetrol-3,20-dione whichcomprises reacting a A -pregnenel1B,170,21-triol-3,20-dione-5a,6a-oxideZI-acetate 3,20- bis-lower alkylene ketal with aluminum hydride in thepresence of a solvent, adding a mineral acid to hydrolyze the resultinghydroxy pregnane and recovering said compound therefrom. v

8. A method of preparing pregnane-5a,l1fi,l7a,2ltetrol-3,20-dione whichcomprises reacting a A -pregnenel1,8,l7a,2l-trio1-3,20-dione-5u,6a-oxideZI-acetate 3,20-

bisethylene ketal with lithium aluminum hydride in the presence of asolvent, adding a mineral acid to hydrolyze the resulting hydroxypregnane and recovering said compound therefrom.

9. In a method of preparing pregnane-5a,11 8,17a,21-

'tetrol-3,20-dione the steps which comprise reactingpregnane-llfi,l7a,21-tetrol-3,20-dione-5a,6u-oxide 21-acetate3,20-bisethylene ketal in tetrahydrofuran in the presence of lithiumaluminum hydride, adding a mineral acid and 10 recovering the saidcompound therefrom.

No references cited.

1. A COMPOUND OF THE GROUP HAVING THE GENERAL FORMULA: